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Properties of transparent elastomer nanocomposites (polyurethane/ ZrO2:Eu3+) as materials for optoelectronic application
|Ewelina A. Zawadzak , Krzysztof J. Kurzydlowski , Joanna Ryszkowska
Warsaw University of Technology, Faculty of Materials Science and Engineering (InMat), Wołoska 141, Warszawa 02-507, Poland
Polyurethanes are engineering materials with useful physical and chemical properties. Polyurethanes copolymers consist of alternating flexible and rigid segments of different polarity. As a result they exhibit a tendency for phase separation, which depends on the length of segments, tendency for crystallization and the overall composition. This phase separation results in the formation of hard and soft domains in polyurethanes and influences their transparency.
Nanocrystalline powders have recently attracted great interest because of their unique properties, including optical ones. It has been shown that nano-ZrO2 is an excellent host material to Eu3+ ions for luminophors. In the present study nanocomposites consisting of transparent PUR and ZrO2 powders doped with Eu3+ ions were investigated. These composites have luminescence properties which can have various applications including document protection.
The elasticity of the nano-polyurethane composites depend on the chemistry of the matrix and on nanofiller - concentration, size and shape of particles. It should be noted in this context that inorganic nanofillers have a strong inclination to agglomerate in organic polymers. The methods for preventing this agglomeration have been the subject of the present study, which aimed at optimizing nanofiller distribution and properties of polyurethane nanocomposites.
For PUR synthesis the following chemicals were used: polycaprolactone diol, 4,4’-dicyclohexymethane diisocyanate, chains extenders. As a nanofiller zirconium oxide containing 10% Eu3+ was used. The nanofiller was added at 0.1% of the polymer weight. Different ways of nanofiller incorporation were investigated.
The microstructure of the obtained materials was examined by Atomic Force Microscopy in a Tapping Mode. The size analysis of nanofillers was investigated with HRSEM and TEM. The mechanical (stretching resistance, Young modulus) and thermal (DSC, TGA) properties of polyurethane nanocomposites were also investigated in addition to the analysis of transmittance and luminescence of obtained materials was performed. The results are discussed in terms of the optimizing the microstructure of the composites in question for opto-electronic applications.
We wish to thank Prof. Wiesław Stręk and PhD Dariusz Hreniak, of the Institute of Low Temperature and Structure Research, Polish Academy of Sciences, for performing the transmittance research. The authors thank Prof. Witold Łojkowski from High Pressure Research Center Polish Academy of Science for the ZrO2:Eu3+ powders.
Presentation: Poster at E-MRS Fall Meeting 2009, Symposium I, by Ewelina A. Zawadzak
See On-line Journal of E-MRS Fall Meeting 2009
Submitted: 2009-05-22 16:51 Revised: 2009-06-07 00:48